Spectrophotometric determination of iron in process samples from the chemical cleaning of coal.

Iron is removed during the desulphurization and demineralization of coal by a chemical cleaning process utilizing a mixture of molten sodium hydroxide and potassium hydroxide. When 1,10-phenanthroline is used for spectrophotometric determination of the iron in the various caustic, aqueous and acidic process streams, organic materials leached from the coal by the molten caustic interfere with the colour-forming reaction. Pre-oxidation of the samples with potassium persulphate has proved to be an effective means of removing the interfering organic material before the iron determination.

Analytical investigation of the properties and uses of a new hydrophobic molecular sieve.

Distribution coefficients and capacities have been determined for many different organic compounds on a new molecular sieve called silicalite, which does not adsorb water but does adsorb small organic molecules with diameters up to 6 A, from both liquid and gaseous streams. The characteristics of silicalite have been examined closely and new applications for it are briefly described.

Selective concentration of amines from aqueous solutions by a gas purging technique.

Amines are removed from heated, basic solutions saturated with salt by inert gas stripping and selectively trapped as coordination complexes on columns containing copper(II) salts coated on an inert support. An estimate of the amine concentrations at ppm levels can be made by measuring the length of the trapping column colored by the complexes. Concentrations of amines in ppb can be determined by eluting this column with potassium hydroxide and determining the amines in the effluent directly by gas chromatography. The procedure allows amines to be concentrated by a factor of 200 and removes potentially interfering substances from the sample.

New chromogens of the ferroin type-VII Some 3-substituted-1,2,4-triazines, 3,5-disubstituted-1,2,4-triazolines and triazoles, and 2,4- and 2,6-bis triazinyl and triazolinyl substituted pyridines.

Chelation and chromogenic properties of 39 new ferroin compounds in reactions with iron(II), copper(I), and cobalt(II) have been investigated spectrophotometrically. The results demonstrate that the chromogenic properties of triazole and triazoline heterocycles are inferior to triazine and pyridine when incorporated into the ferroin chromophore grouping. The triazole and triazoline compounds also undergo hydrolytic decomposition, strongly catalysed by iron(II), making them unsuitable as colorimetric reagents. An outstanding chromogen was found from among the triazine derivatives which is superior in sensitivity to all ferroin-type chromogens previously studied.